[slothoncoffee]

https://imgur.com/U6VqmIF

I don't understand why the intermediate product of the first reaction isn't an alkene at the C2=C3. E2 rxn should need a bulky base to favor the less stable C1=C2?

I understand the rest of the steps. Any help is very appreciated!

[spirochete]

The internal alkyne is a little bit more stable and might form faster at first. But formation fo the internal alkyne is reversible.

But there is a proton transfer at the end of the mechanism that causes the formation of the terminal alkyne to be irreversible. The amide ion (NH2-) is a strong enough base to deprotonate a terminal alkyne.

If a weaker base such as sodium hydroxide is used for the elimination, then an internal alkyne will be the major product. That's because hydroxide is not a strong enough base to deprotonate a terminal alkyne.

This is discussed in the organic chemistry textbook by Wade, and probably others.

[slothoncoffee]

Thank you very much, Spirochete! That's very helpful!